1. Field of the Invention
The present invention relates to an image data processing circuit and an image forming apparatus having the same and, more specifically, to an image data processing circuit that executes a first image processing for an image read by a scanner unit, stores an image signal thereof in a page memory, and reads the image signal from the page memory according to a synchronous signal generated in an engine unit to execute a second image processing, and a color image forming apparatus that executes an image formation in the engine unit using the result of process executed by the image data processing circuit.
2. Description of the Related Art
The color image forming apparatus (MFP) can be categorized roughly into a four-rotation machine and a quadruple tandem machine. In the four-rotation machine, in order to print in the color order (for example, in the order of Y→M→C→K), a single-color process is basically executed in a part from the page memory on of the path of scanner→page memory→printer (processing step), and hence a processing circuit for processing image data for a single-color printing must simply be provided. On the other hand, in the case of the quadruple tandem machine, since the YMCK colors are processed simultaneously even though the printing timing is different due to the positions of the drums, the processing circuits for four colors are necessary.
In the case of the quadruple tandem machine, registers for the respective colors that can cope with four-color simultaneous processing are provided as described above, while in the case of the four-rotation machines, since the time between colors (from a moment when a printing process in a specific printing color is ended to a moment when the process in the next color is started) is short, and hence rewriting of the registers (several tens thousands) by normal access of the CPU cannot be finished within the time between colors. Therefore, registers for four colors that are not used simultaneously are provided to be switched for use. As a document that discloses a technology which is similar to the one shown above, JP-A-2004-274271 is known. There is also JP-A-2004-127033 as another document that discloses a technology related thereto.
However, in the technology disclosed in the above-described documents, the scale of the circuit is increased when integrating the processing circuit, which may result in cost increase. Also, there is a problem such that since the processing circuit for the four-rotation machine and the processing circuit for the quadruple tandem machine cannot be shared, the number of products manufactured cannot be increased although the development cost and the number of management steps of large scale integration increase, whereby improvement of productivity is difficult.